Managing schema evolution in a container‐based persistent system

Abstract

Managing schema evolution is a problem every persistent system has to cope with to be useful in practice. Schema evolution consists basically of supporting class modification and dealing with data objects created and stored under the old class definitions. Several proposals have been made to handle this problem in systems that follow a full orthogonally persistent approach, but, until now, there has not been any proposal to support it in container‐based persistent systems. In this paper we describe a schema evolution management system designed for Barbados. Barbados is a complete programming environment which is based on an architecture of containers to provide persistent storage. Barbados does not provide full orthogonal persistence, but, as will be described in this paper, its architecture has several other advantages. Among them is the fact that this model is especially suitable for solving the schema evolution problem. Copyright © 2002 John Wiley & Sons, Ltd.

Separating adaptable persistence attributes through computational reflection

“…requiring a parser to translate XML documents into objects and the other way round. Besides this impedance mismatch [2], these approaches require the programmer to write code sentences explicitly in order to make objects persist. The main reason of this lack of transparency is that programming languages and database management systems have historically evolved separate from one another, producing substantial differences between their computational models.…”

“…In the Java world, PJama and PEVM are two well-known implementations of the Object Persistence Java platform (OPJ) [3]. The main drawback of existing implementations is that the persistence by reachability rule makes them not fulfill the first criterion of persistence independence [2]. Persistence is not taken into account as a completely separate concern, regarding the SoC principle.…”